Cross-linking of polymer layer on monodispersed poly(maleic anhydride-styrene)-modified colloidal silica particles, and properties of carboxyl and amino group formed on the surface

Surface cross-linking of monodispersed, polymer-modified silica particles, which were prepared by reaction of the colloidal silica with poly(maleic anhydride-styrene) silane coupling agent, with di- or tri-ol and di- or tri-amine, and properties of simultaneously formed carboxyl and amino groups were studied. The copolymer-modified particles were composed of silyl ester bonds (Si-O-CO-) along with siloxane bonds (Si-O-Si-). The reaction of the composite with di- or tri-amine gave composite particles with higher cross-link density, as compared with those derived by the reaction with diols and glycerol, with 12-39 μmol/ amino groups, being unable to bind a secondary polymer of carboxyl group-terminated poly(methyl methacrylate). The cross-linking of the copolymer-modified particles with the alcohols afforded 0.9-1.3 μmol/g surface carboxyl groups, which were able to bind 11-22 mg/g poly(methyl methacrylate) with an amino end group. The aminated and carboxylated silica particles exhibited lower ζ-potential in an aqueous solution than the original colloidal silica.